Liquid crystal composition and liquid crystal display device

ABSTRACT

A liquid crystal composition that satisfies at least one characteristic, such as, high maximum temperature of a nematic phase, low minimum temperature of a nematic phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, large specific resistance, large elastic constant, high stability to ultraviolet light and high stability to heat, or that is suitably balanced between at least two of the characteristics; and provides an AM device that has short response time, large voltage holding ratio, large contrast ratio, long service life and so forth. A liquid crystal composition is provided that has a nematic phase and includes a specific three-ring compound having a large dielectric anisotropy as a first component, a specific four-ring compound having a high maximum temperature and a large dielectric anisotropy as a second component, and a liquid crystal display device containing the composition.

This is a Non-Provisional application, which claims priority to JapanesePatent Application No. 2010-272716, filed on Dec. 7, 2010, the contentsof which are all herein incorporated by this reference in theirentireties. All publications, patents, patent applications, databasesand other references cited in this application, all related applicationsreferenced herein, and all references cited therein, are incorporated byreference in their entirety as if restated here in full and as if eachindividual publication, patent, patent application, database or otherreference were specifically and individually indicated to beincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates mainly to a liquid crystal composition suitablefor use in an AM (active matrix) device and so forth, and an AM deviceand so forth that contain the composition. More specifically, theinvention relates to a liquid crystal composition having positivedielectric anisotropy, and a device containing the composition andhaving a mode such as TN (a twisted nematic) mode, an OCB (opticallycompensated bend) mode, an IPS (in-plane switching) mode, a FFS (fringefield switching) mode or a PSA (polymer sustained alignment) mode.

2. Related Art

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes modes of PC (a phasechange), TN (twisted nematic), STN (super twisted nematic), ECB(electrically controlled birefringence), OCB (optically compensatedbend), IPS (in-plane switching), VA (vertical alignment), FFS (fringefield switching) and PSA (polymer sustained alignment). A classificationbased on a driving mode in the device includes PM (a passive matrix) andAM (an active matrix). The PM is further classified into static,multiplex and so forth, and the AM is classified into TFT (a thin filmtransistor), MIM (a metal-insulator-metal) and so forth. The TFT isfurther classified into amorphous silicon and polycrystal silicon. Thelatter is classified into a high temperature type and a low temperaturetype according to the production process. A classification based on alight source includes a reflection type utilizing natural light, atransmission type utilizing a backlight and a semi-transmission typeutilizing both natural light and a backlight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to give anAM device having good general characteristics. Table 1 below summarizesthe relationship between the general characteristics of the two. Thegeneral characteristics of the composition will be explained furtherbased on a commercially available AM device. The temperature range of anematic phase relates to the temperature range in which the device canbe used. A desirable maximum temperature of the nematic phase isapproximately 70° C. or higher and a desirable minimum temperature ofthe nematic phase is approximately −10° C. or lower. The viscosity ofthe composition relates to the response time of the device. A shortresponse time is desirable for displaying moving images on the device.Accordingly, a small viscosity of the composition is desirable. A smallviscosity at a low temperature is more desirable. The elastic constantof the composition relates to the contrast of the device. A largeelastic constant of the composition is desirable for increasing thecontrast of the device.

TABLE 1 General Characteristics of Composition and AM Device GeneralGeneral No. Characteristics of Composition Characteristics of AM Device1 wide temperature range of a wide usable temperature range nematicphase 2 small viscosity ¹⁾ short response time 3 suitable opticalanisotropy large contrast ratio 4 large positive or negative dielectriclow threshold voltage and small anisotropy electric power consumptionlarge contrast ratio 5 large specific resistance large voltage holdingratio and large contrast ratio 6 high stability to ultraviolet lightlong service life and heat 7 large elastic constant short response timeand large contrast ratio ¹⁾ A liquid crystal composition can be injectedinto a liquid crystal cell in a shorter period of time.

The optical anisotropy of the composition relates to the contrast ratioof the device. The product (Δn×d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends onthe kind of operating mode. In a device having a TN mode, a suitablevalue is approximately 0.45 micrometer. In this case, a compositionhaving a large optical anisotropy is desirable for a device having asmall cell gap. A large dielectric anisotropy of the compositioncontributes to a low threshold voltage, small electric power consumptionand a large contrast ratio of the device. Accordingly, a largedielectric anisotropy is desirable. A large specific resistance of thecomposition contributes to a large voltage holding ratio and a largecontrast ratio of the device. Accordingly, a composition having a largespecific resistance is desirable at room temperature and also at atemperature close to the maximum temperature of a nematic phase in theinitial stage. A composition having a large specific resistance isdesirable at room temperature and also at a temperature close to themaximum temperature of a nematic phase after it has been used for a longtime. The stability of the composition to ultraviolet light and heatrelates to the service life of the liquid crystal display device. In thecase where the stability is high, the device has a long service life.These characteristics are desirable for an AM device used in a liquidcrystal projector, a liquid crystal television and so forth. A largeelastic constant of the composition contributes to a large contrastratio and a short response time of the device. Accordingly, a largeelastic constant is desirable.

A composition having positive dielectric anisotropy is used for an AMdevice having a TN mode. On the other hand, a composition havingnegative dielectric anisotropy is used for an AM device having a VAmode. A composition having positive or negative dielectric anisotropy isused for an AM device having an IPS mode or a FFS mode. A compositionhaving positive or negative dielectric anisotropy is used for an AMdevice having a PSA mode. Examples of liquid crystal compositions havingpositive dielectric anisotropy are disclosed in the following patentdocuments 1 to 4.

-   -   Patent document No. 1: JP 2006-089703 A.    -   Patent document No. 2: JP 2008-133470 A.    -   Patent document No. 3: WO 2010/050324 A.    -   Patent document No. 4: WO 2010/090076 A.

A desirable AM device has characteristics such as a wide temperaturerange in which the device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. Response time that is even one millisecondshorter than that of the other devices is desirable. Thus, a compositionhaving characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of a nematic phase, a small viscosity,a suitable optical anisotropy, a large dielectric anisotropy, a largespecific resistance, a high stability to ultraviolet light, a highstability to heat and a large elastic constant is desirable.

SUMMARY OF THE INVENTION

The invention concerns a liquid crystal composition having a nematicphase, wherein a first component is at least one compound selected fromthe group of compounds represented by formula (1), a second component isat least one compound selected from the group of compounds representedby formula (2), and also concerns a liquid crystal display devicecontaining the composition:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring A and ring B are each independently 1,4-cyclohexylene, or1,4-phenylene; X¹, X² and X³ are each independently hydrogen orfluorine; Y¹ is fluorine, chlorine or trifluoromethoxy.

DETAILED DESCRIPTION OF THE INVENTION

Usage of the terms in the specification and claims is as follows. Theliquid crystal composition of the invention and the liquid crystaldisplay device of the invention may be abbreviated to “the composition”and “the device,” respectively. “A liquid crystal display device” is ageneric term for a liquid crystal display panel and a liquid crystaldisplay module. “A liquid crystal compound” is a generic term for acompound having a liquid crystal phase such as a nematic phase or asmectic phase, and also for a compound having no liquid crystal phasesbut being useful as a component of a composition. Such a compound has asix-membered ring such as 1,4-cyclohexylene and 1,4-phenylene, and arod-like molecular structure. An optically active compound and apolymerizable compound may occasionally be added to the composition.Even in the case where these compounds are liquid crystalline, thecompounds are classified as an additive herein. At least one compoundselected from the group of compounds represented by formula (1) may beabbreviated to “the compound (1).” “The compound (1)” means onecompound, or two or more compounds represented by formula (1). The samerules apply to compounds represented by the other formulas. “Arbitrary”is used not only in cases where the position is arbitrary but also incases where the number is arbitrary. However, it is not used in caseswhere the number is 0 (zero).

A higher limit of the temperature range of a nematic phase may beabbreviated to “the maximum temperature.” A lower limit of thetemperature range of a nematic phase may be abbreviated to “the minimumtemperature.” That “specific resistance is large” means that acomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of a nematic phase inthe initial stage, and that the composition has a large specificresistance at room temperature and also at a temperature close to themaximum temperature of a nematic phase even after it has been used for along time. That “a voltage holding ratio is large” means that a devicehas a large voltage holding ratio at room temperature and also at atemperature close to the maximum temperature of a nematic phase in theinitial stage, and that the device has a large voltage holding ratio atroom temperature and also at a temperature close to the maximumtemperature of a nematic phase even after it has been used for a longtime. When characteristics such as optical anisotropy are explained,values which are obtained according to the measuring methods describedin Examples will be used. A first component means one compound, or twoor more compounds. “The ratio of the first component” is expressed as apercentage by weight (% by weight) of the first component based on thetotal weight of the liquid crystal composition. The same rule applies tothe ratio of a second component and so forth. The ratio of an additivemixed with the composition is expressed as a percentage by weight (% byweight) or weight parts per million (ppm) based on the total weight ofthe liquid crystal composition.

The symbol R¹ is used for a plurality of compounds in the chemicalformulas of component compounds. Two groups represented by R1 may be thesame or different in arbitrary two of these compounds. In one case, forexample, R¹ of the compound (1) is ethyl and R¹ of the compound (1-1) isethyl. In another case, R¹ of the compound (1) is ethyl and R¹ of thecompound (1-1) is propyl. The same rule applies to the symbols R² and R³and so forth.

One of the advantages of the invention is to provide a liquid crystalcomposition that satisfies at least one of characteristics such as ahigh maximum temperature of a nematic phase, a low minimum temperatureof a nematic phase, a small viscosity, a suitable optical anisotropy, alarge dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light, a high stability to heat and a largeelastic constant. Another advantage is to provide a liquid crystalcomposition that is suitably balanced between at least two of thecharacteristics. A further advantage is to provide a liquid crystaldisplay device that contains such a composition. An additional advantageis to provide a composition that has a suitable optical anisotropy, alarge dielectric anisotropy, a high stability to ultraviolet light, alarge elastic constant and so forth, and is to provide an AM device thathas a short response time, a large voltage holding ratio, a largecontrast ratio, a long service life and so forth.

The liquid crystal composition of the invention satisfied at least oneof characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of a nematic phase, a small viscosity,a suitable optical anisotropy, a large dielectric anisotropy, a largespecific resistance, a high stability to ultraviolet light, a highstability to heat and a large elastic constant. The liquid crystalcomposition was suitably balanced between at least two of thecharacteristics. The liquid crystal display device contained such acomposition. The composition had a suitable optical anisotropy, a largedielectric anisotropy, a high stability to ultraviolet light, a largeelastic constant and so forth, and the AM device had a short responsetime, a large voltage holding ratio, a large contrast ratio, a longservice life and so forth.

The invention includes the following items.

1. A liquid crystal composition having a nematic phase and comprisingthree components, wherein a first component is at least one compoundselected from the group of compounds represented by formula (1), and asecond component is at least one compound selected from the group ofcompounds represented by formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring A and ring B are each independently 1,4-cyclohexylene or1,4-phenylene, X¹, X² and X³ are each independently hydrogen orfluorine; Y¹ is fluorine, chlorine or trifluoromethoxy.

2. The liquid crystal composition according to item 1, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-1) and formula (1-2):

wherein R¹ is independently alkyl having 1 to 12 carbons, alkoxy having1 to 12 carbons or alkenyl having 2 to 12 carbons.

3. The liquid crystal composition according to item 2, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-1).

4. The liquid crystal composition according to any one of items 1 to 3,wherein the second component is at least one compound selected from thegroup of compounds represented by formula (2-1) and formula (2-2):

wherein R² is independently alkyl having 1 to 12 carbons, alkoxy having1 to 12 carbons or alkenyl having 2 to 12 carbons.

5. The liquid crystal composition according to item 4, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-1).

6. The liquid crystal composition according to any one of items 1 to 5,wherein the ratio of the first component is in the range ofapproximately 5% by weight to approximately 50% by weight, the ratio ofthe second component is in the range of approximately 5% by weight toapproximately 50% by weight, based on the total weight of the liquidcrystal composition.

7. The liquid crystal composition according to any one of items 1 to 6,further comprising at least one compound selected from the group ofcompounds represented by formula (3) as a third component:

wherein R³ and R⁴ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring C, ring D and ring E are each independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z¹ isindependently a single bond, ethylene or carbonyloxy; and m is 0, 1 or2.

8. The liquid crystal composition according to item 7, wherein the thirdcomponent is at least one compound selected from the group of compoundsrepresented by formula (3-1) to formula (3-13):

wherein R³ and R⁴ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkoxymethyl having 2 to 12 carbons,alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons inwhich arbitrary hydrogen is replaced by fluorine.

9. The liquid crystal composition according to item 8, wherein the thirdcomponent is at least one compound selected from the group of compoundsrepresented by formula (3-1).

10. The liquid crystal composition according to item 8, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-7).

11. The liquid crystal composition according to item 8, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1) and formula (3-10).

12. The liquid crystal composition according to item 8, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-1), at least one compoundselected from the group of compounds represented by formula (3-7), andat least one compound selected from the group of compounds representedby formula (3-10).

13. The liquid crystal composition according to any one of items 7 to 12wherein the ratio of the third component is in the range ofapproximately 30% by weight to approximately 75% by weight based on thetotal weight of the liquid crystal composition.

14. The liquid crystal composition according to any one of items 1 to13, further comprising at least one compound selected from the group ofcompounds represented by formula (4) as a fourth component:

wherein R⁵ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring F is independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, 1,3-dioxane-2,5-diylor tetrahydropyran-2,5-diyl or pyrimidine-2,5-diyl; X⁴ and X⁵ are eachindependently hydrogen or fluorine; Y² is fluorine or chlorine; and Z²is independently a single bond, ethylene, carbonyloxy ordifluoromethyleneoxy; n is 1, 2 or 3; and three of Z² are all singlebonds when n is 3.

15. The liquid crystal composition according to item 14, wherein thefourth component is at least one compound selected from the group ofcompounds represented by formula (4-1) to formula (4-19):

wherein R⁵ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.

16. The liquid crystal composition according to item 15, wherein thefourth component is at least one compound selected from the group ofcompounds represented by formula (4-13).

17. The liquid crystal composition according to item 15, wherein thefourth component is at least one compound selected from the group ofcompounds represented by formula (4-14).

18. The liquid crystal composition according to any one of items 14 to17, wherein the ratio of the fourth component is in the range ofapproximately 3% by weight to approximately 40% by weight based on thetotal weight of the liquid crystal composition.

19. The liquid crystal composition according to any one of items 1 to18, further including at least one compound selected from the group ofcompounds represented by formula (5) as a fifth component:

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring G and ring H are eachindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, or 3,5-difluoro-1,4-phenylene; X⁶ and X⁷ areeach independently hydrogen or fluorine; Y³ is fluorine, chlorine ortrifluoromethoxy.

20. The liquid crystal composition according to item 19, wherein thefifth component is at least one compound selected from the group ofcompounds represented by formula (5-1) to formula (5-5):

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.

21. The liquid crystal composition according to item 20, wherein thefifth component is at least one compound selected from the group ofcompounds represented by formula (5-1).

22. The liquid crystal composition according to item 19 to 21, whereinthe ratio of the fifth component is in the range of approximately 3% byweight to approximately 20% by weight based on the total weight of theliquid crystal composition.

23. The liquid crystal composition according to any one of items 1 to22, wherein the maximum temperature of a nematic phase is approximately70° C. or higher, the optical anisotropy (25° C.) at a wavelength of 589nanometers is approximately 0.08 or more, and the dielectric anisotropy(25° C.) at a frequency of 1 kHz is approximately 4 or more.

24. A liquid crystal display device containing the liquid crystalcomposition according to any one of items 1 to 23.

25. The liquid crystal display device according to item 24, wherein anoperating mode of the liquid crystal display device is a TN mode, an OCBmode, an IPS mode, a FFS mode or a PSA mode, and a driving mode of theliquid crystal display device is an active matrix mode.

26. Use of the liquid crystal composition in the liquid crystal displaydevice according to any one of items 1 to 23.

The invention further includes the following items: (1) the compositiondescribed above, further including an optically active compound; (2) thecomposition described above, further including an additive, such as anantioxidant, an ultraviolet light absorber, an antifoaming agent, apolymerizable compound and/or a polymerization initiator; (3) an AMdevice containing the composition described above; (4) a device having amode of TN, ECB, OCB, IPS, FFS or PSA and containing the compositiondescribed above; (5) a transmission-type device containing thecomposition described above; (6) use of the composition described aboveas a composition having a nematic phase; and (7) use of the compositionprepared by the addition of an optically active compound to thecomposition described above, as an optically active composition.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, main characteristics of the componentcompounds and main effects of these compounds on the composition will beexplained. Third, a combination of components in the composition,desirable ratios of the component and the basis thereof will beexplained. Fourth, a desirable embodiment of the component compoundswill be explained. Fifth, specific examples of the component compoundswill be shown. Sixth, additives that may be mixed with the compositionwill be explained. Seventh, methods for synthesizing the componentcompounds will be explained. Last, use of the composition will beexplained.

First, the constitution of component compounds in the composition willbe explained. The compositions of the invention are classified into thecomposition A and the composition B. The composition A may furtherinclude any other liquid crystal compound, an additive and an impurityin addition to a compound selected from the compound (1), the compound(2), the compound (3), the compound (4) and the compound (5). “Any otherliquid crystal compound” is a liquid crystal compound that is differentfrom the compound (1), the compound (2), the compound (3), the compound(4) and the compound (5). Such a compound is mixed with the compositionfor the purpose of further adjusting characteristics of the composition.The additive includes an optically active compound, an antioxidant, anultraviolet light absorber, a coloring matter, an antifoaming agent, apolymerizable compound and a polymerization initiator. The impurity iscompounds and so forth which have contaminated component compounds in aprocess such as their synthesis. Even in the case where the compound isliquid crystalline, it is classified into the impurity herein.

The composition B consists essentially of compounds selected from thegroup of the compound (1), the compound (2), the compound (3), thecompound (4) and the compound (5). The term “essentially” means that thecomposition may also include an additive and an impurity, but does notinclude any liquid crystal compound other than these compounds. Thecomposition B has a smaller number of components than the composition A.The composition B is preferable to the composition A in view of costreduction. The composition A is preferable to the composition B in viewof the fact that physical properties can be further adjusted by addingany other liquid crystal compound.

Second, main characteristics of the component compounds and main effectsof the compounds on the characteristics of the composition will beexplained. The main characteristics of the component compounds aresummarized in Table 2 on the basis of the effects of the invention. InTable 2, the symbol L stands for “large” or “high”, the symbol M standsfor “medium”, and the symbol S stands for “small” or “low.” The symbolsL, M and S are classified according to a qualitative comparison amongthe component compounds, and 0 (zero) means that “a value is nearlyzero.”

TABLE 2 Characteristics of compounds Compound Compound Compound CompoundCompound Compounds (1) (2) (3) (4) (5) Maximum S L S-L S-L M TemperatureViscosity M L S-L M-L L Optical L M-L S-L M-L M-L Anisotropy DielectricL M-L 0 M-L L Anisotropy Specific L L L L L Resistance

Main effects of the component compounds on the characteristics of thecomposition upon mixing the component compounds with the composition areas follows. The compound (1) significantly increases the dielectricanisotropy. The compound (2) increases the maximum temperature, andincreases the dielectric anisotropy. The compound (3) decreases theminimum temperature, and decreases the viscosity. The compound (4)decreases the minimum temperature and increases the dielectricanisotropy. The compound (5) increases the dielectric anisotropy.

Third, a combination of the components in the composition, desirableratios of the component compounds and the basis thereof will beexplained. A combination of the components in the composition is thefirst and second components, the first, second and third components, thefirst, second and fourth components, the first, second and fifthcomponents, the first, second, third and fourth components, the first,second, third and fifth components, the first, second, fourth and fifthcomponents, and the first, second, third, fourth and fifth components. Adesirable combination of the components in the composition is the first,second, third and fourth components and the first, second, third, fourthand fifth components.

A desirable ratio of the first component is approximately 5% by weightor more for increasing the dielectric anisotropy, and approximately 50%by weight or less for decreasing the minimum temperature. A moredesirable ratio is in the range of approximately 7% by weight toapproximately 35% by weight. An especially desirable ratio is in therange of approximately 10% by weight to approximately 20% by weight.

A desirable ratio of the second component is approximately 5% by weightor more for increasing the dielectric anisotropy, and approximately 50%by weight or less for decreasing the minimum temperature. A moredesirable ratio is in the range of approximately 5% by weight toapproximately 35% by weight. An especially desirable ratio is in therange of approximately 5% by weight to approximately 20% by weight.

A desirable ratio of the third component is approximately 30% by weightor more for decreasing the viscosity, and approximately 75% by weight orless for increasing the dielectric anisotropy. A more desirable ratio isin the range of approximately 40% by weight to approximately 70% byweight. An especially desirable ratio is in the range of approximately50% by weight to approximately 65% by weight.

A desirable ratio of the fourth component is approximately 3% by weightor more for increasing the dielectric anisotropy, and approximately 40%by weight or less for decreasing the minimum temperature. A moredesirable ratio is in the range of approximately 5% by weight toapproximately 35% by weight. An especially desirable ratio is in therange of approximately 10% by weight to approximately 30% by weight.

The fifth component is suitable to prepare a composition having a highmaximum temperature and a large dielectric anisotropy. A desirable ratioof the fifth component is in the range of approximately 3% by weight toapproximately 20% by weight. A more desirable ratio is in the range ofapproximately 3% by weight to approximately 15% by weight. An especiallydesirable ratio is in the range of approximately 3% by weight toapproximately 10% by weight.

Fourth, a desirable embodiment of the component compounds will beexplained. R¹, R², R⁵ and R⁶ are each independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons. Desirable R¹, R², R⁵ or R⁶ is alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or for increasing thestability to heat. R³ and R⁴ are each independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,or alkenyl having 2 to 12 carbons in which arbitrary hydrogen isreplaced by fluorine. Desirable R³ or R⁴ is alkenyl having 2 to 5carbons for decreasing the viscosity, and alkyl having 1 to 7 carbonsfor increasing the stability to ultraviolet light or for increasing thestability to heat.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl or heptylfor decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl for decreasing theviscosity. A desirable configuration of —CH═CH— in the alkenyl dependson the position of the double bond. Trans is preferable in the alkenylsuch as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl and3-hexenyl for decreasing the viscosity. Cis is preferable in the alkenylsuch as 2-butenyl, 2-pentenyl and 2-hexenyl. In the alkenyl,straight-chain alkenyl is preferable to branched-chain alkenyl.

Desirable examples of alkenyl in which arbitrary hydrogen is replaced byfluorine are 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More desirable examples are 2,2-difluorovinyland 4,4-difluoro-3-butenyl for decreasing the viscosity.

The alkyl does not include cycloalkyl. The alkoxy does not includecycloalkoxy. The alkenyl does not include cycloalkenyl. That the alkenylin which arbitrary hydrogen is replaced by fluorine does not includecycloalkenyl in which arbitrary hydrogen is replaced by fluorine.Regarding the configuration of 1,4-cycrohexylene, trans is preferable tocis for increasing the maximum temperature.

Ring A and ring B are each independently 1,4-cyclohexylene, or1,4-phenylene. Desirable ring A is 1,4-cycrohexylene for decreasing theviscosity, and desirable ring B is 1,4-phenylene for increasing theoptical anisotropy. Ring C, ring D and ring E are each independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene. Two rings E maybe the same or different when m is 2. Desirable ring C, ring D or ring Eare 1,4-phenylene or 3-fluoro-1,4-phenylene for increasing the opticalanisotropy, and 1,4-cyclohexylene for decreasing the viscosity. Ring Fis 1,4-cycrohexylene, 1,4-phenylene, 2-fluoro-1,4phenylene,3,5-difluoro-1,4-phenylene, 1,3-dioxane-2,5-diyl,tetrahydropyran-2,5-diyl or 2,5-pyrimidine-2,5-diyl, two rings F may besame or different when n is 2 or 3. Desirable ring F is1,4-cycrohexylene for increasing the maximum temperature, and1,4-phenylene for increasing the optical anisotropy. Rings G and H areeach independently 1,4-cycrohexylene, 1,4-phenylene,2-fluoro-1,4phenylene, 3-fluoro-1,4-phenylene or3,5-difluoro-1,4-phenylene. Desirable ring G or H is 1,4phenylene, or3-fluoro-1,4-phenylene for increasing the optical anisotropy.

Z¹ is a single bond, ethylene or carbonyloxy, and two of Z¹ may be thesame or different when m is 2. Desirable Z¹ is a single bond fordecreasing the viscosity, and carbonyloxy for increasing the maximumtemperature. Z² is a single bond, ethylene, carbonyloxy ordifluoromethyleneoxy, and two of Z² may be the same or different when nis 2. Three of Z² are all single bonds. Desirable Z² is a single bondfor decreasing the viscosity, and difluoromethyleneoxy for increasingthe dielectric anisotropy.

X¹, X², X³, X⁴, X⁵, X⁶ and X⁷ are each independently hydrogen orfluorine. Desirable X¹, X², X³, X⁴, X⁵, X⁶ or X⁷ is fluorine forincreasing the dielectric anisotropy.

Y¹ and Y³ are independently fluorine, chlorine or trifluoromethoxy.Desirable Y¹ or Y³ is fluorine for decreasing the viscosity. Y² isindependently fluorine or chlorine. Desirable Y² is fluorine fordecreasing the viscosity.

m is 0, 1 or 2. Desirable m is 0 for decreasing the viscosity, and 2 forincreasing the maximum temperature. n is 1, 2 or 3. Desirable n is 2 forincreasing the maximum temperature and 3 for increasing the stability toultraviolet light or heat.

Fifth, specific examples of the component compounds will be shown. Inthe desirable compounds described below, R⁷, R⁸, R¹² and R¹³ are eachindependently straight chained alkyl having 1 to 12 carbons. R⁹ isindependently alkyl having 1 to 12 carbons or alkoxy having 1 to 12carbons. R¹⁰ and R¹¹ are each independently straight chained alkylhaving 1 to 12 carbons or straight chained alkenyl having 2 to 12carbons.

Desirable compound (1) are the compounds (1-1-1) and (1-2-1). Moredesirable compound (1) is the compounds (1-1-1). Desirable compound (2)are the compound (2-1-1) and the compound (2-2-1). More desirablecompound (2) is the compound (2-1-1). Desirable compound (3) are thecompound (3-1-1) to the compound (3-13-1). More desirable compound (3)are the compound (3-1-1), the compound (3-5-1), the compound (3-7-1),the compound (3-10-1) and the compound (3-13-1). Especially desirablecompound (3) is the compound (3-1-1). Desirable compound (4) are thecompound (4-1-1) to the compound (4-19-1). More desirable compound (4)are the compound (4-5-1), the compound (4-6-1), the compound (4-13-1),the compound (4-14-1), the compound (4-16-1), the compound (4-18-1) andthe compound (4-19-1). Especially desirable compound (4) are thecompound (4-13-1), the compound (4-14-1), the compound (4-18-1) and thecompound (4-19-1). Desirable compound (5) are the compound (5-1-1) tothe compound (5-5-1). More desirable compound (5) are the compound(5-1-1), the compound (5-3-1) and the compound (5-5-1). Especiallydesirable compound (5) is the compound (5-1-1).

Sixth, additives which may be mixed with the composition will beexplained. Such additives include an optically active compound, anantioxidant, an ultraviolet light absorber, a coloring matter, anantifoaming agent, a polymerizable compound and a polymerizationinitiator. The optically active compound is mixed with the compositionfor the purpose of inducing a helical structure and giving a twist anglein liquid crystals. Examples of such compounds include the compound(6-1) to the compound (6-5). A desirable ratio of the optically activecompound is approximately 5% by weight or less, and a more desirableratio is in the range of approximately 0.01% by weight to approximately2% by weight.

An antioxidant is mixed with the composition in order to prevent adecrease in specific resistance that is caused by heating under air, orto maintain a large voltage holding ratio at room temperature and alsoat a temperature close to the maximum temperature of a nematic phaseafter the device was used for a long time.

Desirable examples of the antioxidant include the compound (7) where pis an integer from 1 to 9. In the compound (7), desirable p is 1, 3, 5,7 or 9. More desirable p is 1 or 7. The compound (7) where p is 1 iseffective in preventing a decrease in specific resistance that is causedby heating under air, because it has a large volatility. The compound(7) where p is 7 is effective in maintaining a large voltage holdingratio at room temperature and also at a temperature close to the maximumtemperature of a nematic phase even after the device has been used for along time, because it has a small volatility. A desirable ratio of theantioxidant is approximately 50 ppm or more for achieving its effect andis approximately 600 ppm or less for avoiding a decrease in the maximumtemperature or avoiding an increase in the minimum temperature. A moredesirable ratio is in the range of approximately 100 ppm toapproximately 300 ppm.

Desirable examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also desirable. A desirable ratio of the ultraviolet light absorberor the light stabilizer is approximately 50 ppm or more for achievingits effect and is approximately 10,000 ppm or less for avoiding adecrease in the maximum temperature or avoiding an increase in theminimum temperature. A more desirable ratio is in the range ofapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition for adjusting to a device having a guest host (GH) mode.A desirable ratio of the coloring matter is in the range ofapproximately 0.01% by weight to approximately 10% by weight. Anantifoaming agent such as dimethyl silicone oil or methyl phenylsilicone oil is mixed with the composition for preventing foamformation. A desirable ratio of the antifoaming agent is approximately 1ppm or more for achieving its effect and is approximately 1,000 ppm orless for avoiding a poor display. A more desirable ratio is in the rangeof approximately 1 ppm to approximately 500 ppm.

A polymerizable compound is mixed with the composition for adjusting toa device having a PSA (polymer sustained alignment) mode. Desirableexamples of the polymerizable compound include compounds having apolymerizable group, such as acrylates, methacrylates, vinyl compounds,vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes,oxetanes) and vinyl ketones. Especially desirable examples of thepolymerizable compound are acrylate derivatives or methacrylatederivatives. A desirable ratio of the polymerizable compound isapproximately 0.05% by weight or more for achieving its effect and isapproximately 10% by weight or less for avoiding a poor display. A moredesirable ratio is in the range of approximately 0.1% by weight toapproximately 2% by weight. The polymerizable compound is polymerized onirradiation with ultraviolet light or the like, preferably in thepresence of a suitable initiator such as a photopolymerizationinitiator. Suitable conditions for polymerization, and a suitable typeand amount of the initiator are known to a person skilled in the art andare described in the literature. For example, Irgacure 651 (registeredtrademark), Irgacure 184 (registered trademark) or Darocure 1173(registered trademark) (available from BASF), each of which is aphotoinitiator, is suitable for radical polymerization. A desirableratio of the photopolymerization initiator is in the range ofapproximately 0.1% by weight to approximately 5% by weight, and anespecially desirable ratio is in the range of approximately 1% by weightto approximately 3% by weight based on the polymerizable compound.

Seventh, methods for synthesizing the component compounds will beexplained. These compounds (1) to (5) can be prepared by known methods.The synthetic methods will be exemplified as follows. The compound(1-1-1) is prepared by the method described in JP H10-251186 A (1998).The compound (2-1-1) is prepared by the method described in JPH10-251186 A (1998). The compound (3-1-1) is prepared by the methoddescribed in JP S59-070624 A (1984) and JP S59-176221 A (1984). Thecompound (3-5-1) is prepared by the method described in JP S57-165328 A(1982) and JP S59-176221 A (1984). The compound (4-5-1) is prepared bythe method described in JP H02-233626 A (1990). The compound (5-1-1) isprepared by the method described in JP H10-251186 A (1998). The compoundwith formula (7) where p is 1 is available from Sigma-AldrichCorporation. The compound (7) where p is 7 or the like is synthesizedaccording to the method described in U.S. Pat. No. 3,660,505.

Compounds whose synthetic methods are not described above can beprepared according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press), Newexperimental Chemistry Course (Shin Jikken Kagaku Kouza, in Japanese;Maruzen Co., Ltd.). The composition is prepared according to knownmethods using the compounds thus obtained. For example, the componentcompounds are mixed and dissolved in each other by heating.

Last, use of the composition will be explained. The composition mainlyhas a minimum temperature of approximately −10° C. or lower, a maximumtemperature of approximately 70° C. or higher, and an optical anisotropyin the range of approximately 0.07 to approximately 0.20. A devicecontaining the composition has a large voltage holding ratio. Thecomposition is suitable for an AM device. The composition is suitableespecially for an AM device having a transmission type. The compositionhaving an optical anisotropy in the range of approximately 0.08 toapproximately 0.25, and also the composition having an opticalanisotropy in the range of approximately 0.10 to approximately 0.30 maybe prepared by adjusting ratios of the component compounds or by mixingwith any other liquid crystal compound. The composition can be used as acomposition having a nematic phase and as an optically activecomposition by adding an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for the AM device and the PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, FFS, VA or PSA.It is especially desirable to use the composition for the AM devicehaving the TN, OCB, IPS or FFS mode. In an AM device having an IPS modeor an FFS mode, the orientation of liquid crystal molecules may beparallel or perpendicular to the panel substrate when no voltage isapplied. These devices may be of a reflection type, a transmission typeor a semi-transmission type. It is desirable to use the composition fora device having the transmission type. It can also be used for anamorphous silicon-TFT device or a polycrystal silicon-TFT device. Thecomposition is also usable for a nematic curvilinear aligned phase(NCAP) device prepared by microcapsulating the composition, and for apolymer dispersed (PD) device in which a three-dimensionalnetwork-polymer is formed in the composition.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

A composition and a compound were a subject for measurement in order toevaluate the characteristics of the composition and the compound thatwill be included in the composition. When the subject for measurementwas a composition, the composition itself was measured as a sample, andthe value obtained was described here. When a subject for measurementwas a compound, a sample for measurement was prepared by mixing 15% byweight of the compound and 85% by weight of mother liquid crystals. Thecharacteristic values of the compound were calculated from valuesobtained by measurement, according to a method of extrapolation. That isto say that (extrapolated value)=[(measured value of a sample formeasurement)−0.85×(measured value of mother liquid crystals)]/0.15. Whena smectic phase (or crystals) separated out in this ratio at 25° C., theratio of the compound to the mother liquid crystals was changed step bystep in the order of (10% by weight/90% by weight), (5% by weight/95% byweight) and (1% by weight/99% by weight). The values of the maximumtemperature, the optical anisotropy, the viscosity and the dielectricanisotropy with regard to the compound were obtained by thisextrapolation method.

The components of the mother liquid crystals were as follows. The ratioswere expressed as a percentage by weight.

Characteristics were measured according to the following methods. Mostare methods described in the JEITA standards (JEITA-ED-2521B) which wasdeliberated and established by Japan Electronics and InformationTechnology Industries Association (abbreviated to JEITA), or themodified methods.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. Thetemperature was measured when part of the sample began to change from anematic phase to an isotropic liquid. A higher limit of the temperaturerange of a nematic phase may be abbreviated to “the maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in glass vials and then kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then the liquid crystal phases were observed. For example,when the sample maintained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., Tc was expressed as <−20° C. Alower limit of the temperature range of a nematic phase may beabbreviated to “the minimum temperature.”

Viscosity (bulk viscosity; η; measured at 20° C.; mPa·s): Viscosity wasmeasured by use of an E-type viscometer.

Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·s):Measurement was carried out according to the method described in M.Imai, et al., Molecular Crystals and Liquid Crystals, Vol. 259, 37(1995). A sample was poured into a TN device in which the twist anglewas 0 degrees and the distance between the two glass substrates (cellgap) was 5 micrometers. A voltage with an increment of 0.5 V in therange of 16 V to 19.5 V was applied stepwise to the device. After aperiod of 0.2 second with no voltage, a voltage was applied repeatedlyunder the conditions of only one rectangular wave (rectangular pulse;0.2 second) and of no voltage (2 seconds). The peak current and the peaktime of the transient current generated by the applied voltage weremeasured. The value of rotational viscosity was obtained from themeasured values and the calculating equation (8) on page 40 of the paperpresented by M. Imai, et al. The value of dielectric anisotropynecessary for this calculation was obtained by use of the device thathad been used for the measurement of this rotational viscosity,according to the method that will be described below.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out by use of an Abbe refractometer with apolarizing plate mounted on the ocular, using light at a wavelength of589 nanometers. The surface of the main prism was rubbed in onedirection, and then a sample was dropped on the main prism. A refractiveindex (n∥) was measured when the direction of polarized light wasparallel to that of the rubbing. A refractive index (n⊥) was measuredwhen the direction of polarized light was perpendicular to that of therubbing. The value of optical anisotropy was calculated from theequation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; measured at 25° C.): A sample was poured intoa TN device in which the distance between the two glass substrates (cellgap) was 9 micrometers and the twist angle was 80 degrees. Sine waves(10 V, 1 kHz) were applied to this device, and a dielectric constant(∈∥) in the major axis direction of liquid crystal molecules wasmeasured after 2 seconds. Sine waves (0.5 V, 1 kHz) were applied to thedevice and a dielectric constant (∈⊥) in the minor axis direction of theliquid crystal molecules was measured after 2 seconds. The value ofdielectric anisotropy was calculated from the equation: Δ∈=∈∥−∈⊥.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. A sample waspoured into a TN device having a normally white mode, in which thedistance between the two glass substrates (cell gap) was about 0.45/Δn(micrometers) and the twist angle was 80 degrees. A voltage to beapplied to the device (32 Hz, rectangular waves) was stepwise increasedin 0.02 V increments from 0 V up to 10 V. During the increase, thedevice was irradiated with light in the perpendicular direction, and theamount of light passing through the device was measured. Avoltage-transmittance curve was prepared, in which the maximum amount oflight corresponded to 100% transmittance and the minimum amount of lightcorresponded to 0% transmittance. The threshold voltage is voltage at90% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweenthe two glass substrates (cell gap) was 5 micrometers. A sample waspoured into the device, and then the device was sealed with an adhesivecurable on irradiation with ultraviolet light. A pulse voltage (60microseconds at 5 V) was applied to the device and the device wascharged. A decreasing voltage was measured for 16.7 milliseconds with ahigh-speed voltmeter, and the area A between the voltage curve and thehorizontal axis in a unit cycle was obtained. The area B was an areawithout the decrease. The voltage holding ratio was the percentage ofthe area A to the area B.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweenthe two glass substrates (cell gap) was 5 micrometers. A sample waspoured into the device, and then the device was sealed with an adhesivecurable on irradiation with ultraviolet light. A pulse voltage (60microseconds at 5 V) was applied to the TN device and the device wascharged. A decreasing voltage was measured for 16.7 milliseconds with ahigh-speed voltmeter and the area A between the voltage curve and thehorizontal axis in a unit cycle was obtained. The area B was an areawithout the decrease. The voltage holding ratio was a percentage of thearea A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): The stability toultraviolet light was evaluated by measuring a voltage holding ratioafter irradiation with ultraviolet light. A TN device used formeasurement had a polyimide-alignment film and the cell gap was 5micrometers. A sample was poured into this device, and then the devicewas irradiated with light for 20 minutes. The light source was an ultrahigh-pressure mercury lamp USH-500D (produced by Ushio, Inc.), and thedistance between the device and the light source was 20 centimeters. Inthe measurement of VHR-3, a decreasing voltage was measured for 16.7milliseconds. A composition having a large VHR-3 has a high stability toultraviolet light. The value of VHR-3 is preferably 90% or more, andmore preferably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A TN device intowhich a sample was poured was heated in a constant-temperature bath at80° C. for 500 hours, and then the stability to heat was evaluated bymeasuring the voltage holding ratio. In the measurement of VHR-4, adecreasing voltage was measured for 16.7 milliseconds. A compositionhaving a large VHR-4 has a high stability to heat.

Response Time (τ; measured at 25° C.; millisecond): Measurement wascarried out with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. The low-passfilter was set at 5 kHz. A sample was poured into a TN device having anormally white mode, in which the cell gap between the two glasssubstrates was 5.0 micrometers and the twist angle was 80 degrees.Rectangular waves (60 Hz, 5 V, 0.5 second) were applied to this device.The device was simultaneously irradiated with light in the perpendiculardirection, and the amount of light passing through the device wasmeasured. The maximum amount of light corresponded to 100%transmittance, and the minimum amount of light corresponded to 0%transmittance. Rise time (τr; millisecond) was the time required for achange from 90% to 10% transmittance. Fall time (τf; millisecond) wasthe time required for a change from 10% to 90% transmittance. Theresponse time was the sum of the rise time and the fall time thusobtained.

Elastic Constant (K; measured at 25° C.; pN): Measurement was carriedout with an LCR meter Model HP 4284A made by Yokogawa-Hewlett-PackardCompany. A sample was put in a homogeneous cell in which the distancebetween the two glass substrates (cell gap) was 20 micrometers. Anelectric charge of 0 V to 20 V was applied to the cell, andelectrostatic capacity and applied voltage were measured. The measuredvalues of the electrostatic capacity (C) and the applied voltage (V)were fitted to equation (2.98) and equation (2.101) on page 75 of LiquidCrystal Device Handbook (Ekishou Debaisu Handobukku, in Japanese; theNikkan Kogyo Shimbun, Ltd.), giving the values of K11 and K33 fromequation (2.99). Next, K22 was calculated form equation (3.18) on page171 using the values of K11 and K33. The elastic constant was theaverage value of K11, K22 and K33 thus obtained.

Specific Resistance (ρ; measured at 25° C.; Ω cm): A sample (1.0milliliters) was poured into a vessel equipped with electrodes. A DCvoltage (10 V) was applied to the vessel, and the DC current wasmeasured after 10 seconds. The specific resistance was calculated fromthe following equation:(specific resistance)=[(voltage)×(electric capacity of vessel)]/[(DCcurrent)×(dielectric constant in vacuum)].

Helical pitch (P; measured at room temperature; micrometer): The helicalpitch was measured according to the wedge method (see page 196 of LiquidCrystal Handbook (Ekishou Binran, in Japanese; Maruzen, Co., Ltd.,2000). After a sample had been injected into a wedge-shaped cell and thecell had been allowed to stand at room temperature for 2 hours, theinterval (d2−d1) of disclination lines was observed with a polarizingmicroscope (Nikon Corporation, Model MM-40/60 series). The helical pitch(P) was calculated from the following equation, where θ was defined asthe angle of the wedge cell: P=2×(d2−d1)×tan θ.

Gas Chromatographic Analysis: A gas chromatograph Model GC-14B made byShimadzu Corporation was used for measurement. The carrier gas washelium (2 milliliters per minute). The sample injector and the detector(FID) were set to 280° C. and 300° C., respectively. A capillary columnDB-1 (length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer, dimethylpolysiloxane as the stationary phase, non-polar)made by Agilent Technologies, Inc. was used for the separation ofcomponent compounds. After the column had been kept at 200° C. for 2minutes, it was further heated to 280° C. at the rate of 5° C. perminute. A sample was dissolved in acetone (0.1% by weight), and 1microliter of the solution was injected into the sample injector. Arecorder used was a Model C-R5A Chromatopac Integrator made by ShimadzuCorporation or its equivalent. The resulting gas chromatogram showed theretention time of peaks and the peak areas corresponding to thecomponent compounds.

Solvents for diluting the sample may also be chloroform, hexane and soforth. The following capillary columns may also be used in order toseparate the component compounds: HP-1 (length 30 meters, bore 0.32millimeter, film thickness 0.25 micrometer) made by Agilent TechnologiesInc., Rtx-1 (length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer) made by Restek Corporation, and BP-1 (length 30 meters, bore0.32 millimeter, film thickness 0.25 micrometer) made by SGEInternational Pty. Ltd. A capillary column CBP1-M50-025 (length 50meters, bore 0.25 millimeter, film thickness 0.25 micrometer) made byShimadzu Corporation may also be used for the purpose of avoiding anoverlap of peaks of the compounds.

The ratio of the liquid crystal compounds included in the compositionmay be calculated according to the following method. The liquid crystalcompounds are detected by use of a gas chromatograph. The ratio of peakareas in the gas chromatogram corresponds to the ratio (molar ratio) ofthe liquid crystal compounds. When the capillary columns described aboveare used, the correction coefficient of respective liquid crystalcompounds may be regarded as 1 (one). Accordingly, the ratio (% byweight) of the liquid crystal compound can be calculated from the ratioof peak areas.

The invention will be explained in detail by way of Examples. Theinvention is not limited by Examples described below. The compoundsdescribed in Comparative Examples and Examples will be expressed interms of symbols according to the definition in the following Table 3.In Table 3, the configuration of 1,4-cyclohexylene is trans. Aparenthesized number next to the symbolized compound in Examplecorresponds to the number of a compound. The symbol (-) means any otherliquid crystal compound. Ratios (percentage) of liquid crystal compoundsmean the percentages by weight (% by weight) based on the total weightof the liquid crystal composition. The liquid crystal compositionfurther includes an impurity. Last, the characteristic values of thecomposition are summarized.

TABLE 3 Method of Description of Compound using Symbols R—(A₁)—Z₁— . . .—Z_(n)—(A_(n))—R′ 1) Left Terminal Group R— Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn— CH₂═CH— V—C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn—C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn— CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn— CH₂═CHCH₂CH₂CH═CHCH₂CH₂— V2V2—C_(n)H_(2n+1)CH₂═CHCH₂CH₂CH═CHCH₂CH₂— nV2V2— 2) Right Terminal Group —R′Symbol —C_(n)H_(2n+1) -n —OC_(n)H_(2n+1) —On —CH═CH₂ —V—CH═CH—C_(n)H_(2n+1) —Vn —C_(n)H_(2n)—CH═CH₂ —nV —CH═CF₂ —VFF —F —F —Cl—CL —OCF₃ —OCF3 —CN —C 3) Bonding group —Zn— Symbol —C₂H₄— 2 —COO— E—CH═CH— V —C≡C— T —CF₂O— X —CH═CH—CF₂O— VX 4) Ring Structure —An— Symbol

H

B

B(F)

B(2F)

B(F,F)

B(2F,5F)

Py

dh

G 5) Example of Description Example 1

Example 2

Example 3

Example 4

Comparative Example 1

Example 2 was selected from the compositions disclosed in JP 2006-089703A. The basis of the selection was that the composition included thecompound (1-1), the compound (3-1-1), the compound (3-5-1) the compound(4-1-1) the compound (4-11-1) the compound (4-14-1) and the compound(4). The components and characteristics of the composition were asfollows. The composition was prepared and measured by the methoddescribed above as the dielectric anisotropy (Δ∈) was not described.

3-BB(F,F)XB(F)—OCF3 (1-1-1)  3% V—HH-5 (3-1-1) 16% 1V—HH-3 (3-1-1) 13%V—HHB-1 (3-5-1) 19% V2-HHB-1 (3-5-1) 10% 3-HB—CL (4-1-1) 11% 2-HBB—F(4-11-1)  4% 3-HBB—F (4-11-1)  4% 3-BB(F,F)XB(F,F)—F (4-14-1) 13%3-HHEB—F (4)  2% 3-HB(F,F)XB(F,F)—F (4)  3% 3-HHB—OCF3 (—)  2%

NI=79.8° C.; Tc≦−30° C.; Δn=0.096; Δ∈=4.4; η=12.6 mPa·s; Vth=1.99V;VHR-1=99.4%; VHR-2=97.4%; τ=9.7 ms.

Comparative Example 2

Example 22 was selected from the compositions disclosed in JP2008-133470 A. The basis of the selection was that the compositionincluded the compound (1-1-1), the compound (3-1-1), the compound(3-5-1) the compound (3-7-1), the compound (4-12-1) the compound(4-13-1), the compound (4-15-1) the compound (4-16-1), the compound(4-17-1) and the compound (4). The components and characteristics of thecomposition were as follows.

2-BB(F,F)XB(F)—OCF3 (1-1-1) 5% V—HH-4 (3-1-1) 5% V—HHB-3 (3-5-1) 5%2-BB(F)B-3 (3-7-1) 5% 2-HBB(F,F)—F (4-12-1) 5% 3-HBB(F,F)—F (4-12-1) 5%5-HBB(F,F)—F (4-12-1) 5% V2V2-BB(F)B(F,F)—F (4-13-1) 10% 1V2V2-BB(F)B(F,F)—F (4-13-1) 10%  5-BB(F,F)XB(F)—F (4-15-1) 5%3-HHBB(F,F)—F (4-16-1) 5% 5-HHBB(F,F)—F (4-16-1) 5% 3-HHB(F)B(F,F)—F(4-16-1) 5% 5-HHB(F)B(F,F)—F (4-17-1) 5% 2-HB(F)B(F,F)—F (4) 5%3-HB(F)B(F,F)—F (4) 5% 5-HB(F)B(F,F)—F (4) 5% 4-BB(F,F)XB(F,F)—OCF3 (—)5%

NI=124.4° C.; Tc≦−20° C.; Δn=0.176; Δ∈=12.4; η=39.1 mPa·s; Vth=1.39V;VHR-1=99.5%.

Comparative Example 3

Example 6 was selected from the compositions disclosed in JP 2010-050324A. The basis of the selection was that the composition included thecompound (1-1-1), the compound (2), the compound (3-1-1) the compound(3-5-1), the compound (3-7-1), the compound (4-2-1) and the compound(5). The composition was prepared and measured by the method describedabove as the bulk viscosity (η) was not described.

The components and characteristics of the composition were as follows.

3-BB(F,F)XB(F)—OCF3 (1-1-1) 6% 3-HHBXB(F)—F (2) 8% 4-HHBXB(F)—F (2) 8%V—HH-3 (3-1-1) 47%  V—HHB-1 (3-5-1) 4% 3-HHB—O1 (3-5-1) 4% V2-BB(F)B-1(3-7-1) 4% V2-BB(F)B-2 (3-7-1) 3% 1V2-BB—F (4-2-1) 4%3-HBB(F,F)XB(F)—OCF3 (5) 4% 4-HBB(F,F)XB(F)—OCF3 (5) 4% 3-HHXB(F)—OCF3(—) 4%

NI=87.4° C.; Tc≦−20° C.; Δn=0.108; Δ∈=3.8; γ1=47.2 mPa·s; η=14.4 mPa·s;τ=6.8 ms; VHR-1=99.3%; VHR-2=98.2%; VHR-1=98.1%.

Example 1

3-BB(F,F)XB(F)—OCF3 (1-1-1) 6% 3-HBBXB(F,F)—F (2-1-1) 7% 5-HBBXB(F,F)—F(2-1-1) 8% V—HH-3 (3-1-1) 40%  V—HHB-1 (3-5-1) 5% 1-BB(F)B-2V (3-7-1) 5%2-BB(F)B-2V (3-7-1) 3% 3-HHXB(F,F)—F (4-6-1) 8% 3-HBB(F,F)—F (4-12-1)10%  3-BB(F,F)XB(F,F)—F (4-14-1) 8%

NI=78.6° C.; Tc≦−20° C.; Δn=0.107; Δ∈=5.8; Vth=1.87 V; η=9.8 mPa·s;VHR-1=99.2%; VHR-2=98.2%; VHR-3=98.1%.

Example 2

3-BB(F,F)XB(F)—OCF3 (1-1-1) 7% 3-HBBXB(F,F)—F (2-1-1) 8% 3-HH-4 (3-1-1)30%  3-HH-5 (3-1-1) 10%  3-HB—O2 (3-2-1) 9% 3-HHB-1 (3-5-1) 4% 3-HHB—O1(3-5-1) 4% 5-HBB(F)B-2 (3-13-1) 4% 5-HB—CL (4-1-1) 8% 2-HHB—CL (4-4-1)3% 3-HHB—CL (4-4-1) 3% 3-BB(F)B(F,F)—F (4-13-1) 4% 3-HHB(F)B(F,F)—F(4-17-1) 3% 4-BB(F)B(F,F)XB(F,F)—F (5-1-1) 3%

NI=88.8° C.; Tc≦−30° C.; Δn=0.098; Δ∈=3.7; Vth=2.10 V; η=10.4 mPa·s;VHR-1=99.0%; VHR-2=98.3%; VHR-3=98.0%.

Example 3

3-BB(F,F)XB(F)—OCF3 (1-1-1) 4% 4-BB(F,F)XB(F)—OCF3 (1-1-1) 4%5-BB(F,F)XB(F)—OCF3 (1-1-1) 4% 3-HBBXB(F,F)—F (2-1-1) 5% 3-HHBXB(F,F)—F(2-2-1) 5% V—HH-3 (3-1-1) 30%  1V—HH-4 (3-1-1) 8% 4-HHEH-3 (3-4-1) 5%4-HHEH-5 (3-4-1) 5% 3-HB(F)HH-5 (3-9-1) 3% 3-HB—CL (4-1-1) 5% 1V2-BB—F(4-2-1) 4% 1V2-BB—CL (4-3-1) 4% 3-HHXB(F,F)—F (4-6-1) 4% 3-HHEB(F,F)—F(4-7-1) 3% 3-HBEB(F,F)—F (4-10-1) 3% 3-BB(F,F)XB(F,F)—F (4-14-1) 4%

NI=72.4° C.; Tc≦−20° C.; Δn=0.086; Δ∈=4.5; Vth=1.97 V; η=9.4 mPa·s;VHR-1=99.1%; VHR-2=98.2%; VHR-3=97.9%.

Example 4

3-BB(F,F)XB(F)—OCF3 (1-1-1) 6% 3-BB(F,F)XB—OCF3 (1-2-1) 5%3-HBBXB(F,F)—F (2-1-1) 6% 4-HBBXB(F,F)—F (2-1-1) 5% V—HH-3 (3-1-1) 30% VFF—HH-3 (3-1) 8% V2-BB-1 (3-3-1) 6% 1V2-HBB-3 (3-6-1) 5% 3-B(F)BB-2(3-8-1) 5% 3-HB(F)BH-3 (3-12-1) 3% 3-HHB(F,F)—F (4-5-1) 5% 3-HGB(F,F)—F(4-8-1) 3% 3-HBB—F (4-11-1) 3% 3-BB(F,F)XB(F)—F (4-15-1) 5%3-BB(F)B(F,F)XB(F)—F (5-2-1) 5%

NI=77.1° C.; Tc≦−20° C.; Δn=0.113; Δ∈=5.4; Vth=1.91 V; η=10.3 mPa·s;VHR-1=99.0%; VHR-2=98.3%; VHR-3=98.0%.

Example 5

2-BB(F,F)XB(F)—OCF3 (1-1-1) 4% 3-BB(F,F)XB(F)—OCF3 (1-1-1) 4%3-HBBXB(F,F)—F (2-1-1) 6% 2-HH-3 (3-1-1) 12%  3-HH—O1 (3-1-1) 5% V—HH-3(3-1-1) 30%  1V2-HH-3 (3-1-1) 5% V—HHB-1 (3-5-1) 5% 1V2-HHB-1 (3-5-1) 4%3-HHEBH-3 (3-10-1) 3% 1-HHXB(F,F)—F (4-6-1) 5% 3-GHB(F,F)—F (4-9-1) 3%3-HHBB(F,F)—F (4-16-1) 3% 3-BBB(F)B(F,F)—F (4-18-1) 3%2-HBB(F,F)XB(F,F)—F (5-3-1) 4% 3-HBB(F,F)XB(F,F)—F (5-3-1) 4%

NI=82.7° C.; Tc≦−20° C.; Δn=0.085; Δ∈=4.0; Vth=2.06 V; η=10.3 mPa·s;VHR-1=99.1%; VHR-2=98.2%; VHR-3=98.0%.

Example 6

3-BB(F,F)XB(F)—OCF3 (1-1-1) 8% 2-HBBXB(F,F)—F (2-1-1) 3% 3-HBBXB(F,F)—F(2-1-1) 3% V—HH-3 (3-1-1) 40%  1V—HH-3 (3-1-1) 3% 7-HB-1 (3-2-1) 3%3-HB—O1 (3-2-1) 3% V—HHB-1 (3-5-1) 6% V2-HHB-1 (3-5-1) 5% 5-HBBH-3(3-11-1) 3% 3-BB(F)B(F,F)—F (4-13-1) 4% 3-BB(F,F)XB(F,F)—F (4-14-1) 7%3-BBB(F,F)B(F,F)—F (4-19-1) 3% 3-BB(F)B(F,F)XB(F,F)—F (5-1-1) 3%3-HB(F)B(F,F)XB(F,F)—F (5-5-1) 3% 3-PyBB—F (—) 3%

NI=76.7° C.; Tc≦−20° C.; Δn=0.099; Δ∈=5.8; Vth=1.87 V; η=9.7 mPa·s;VHR-1=99.0%; VHR-2=98.2%; VHR-3=97.9%.

Example 7

3-BB(F,F)XB(F)—OCF3 (1-1-1) 4% 3-BB(F,F)XB—OCF3 (1-2-1) 4%3-HBBXB(F,F)—F (2-1-1) 4% 3-HBBXB(F)—OCF3 (2) 4% 2-HH-3 (3-1-1) 25% 2-HH-5 (3-1-1) 15%  3-HHB-1 (3-5-1) 6% 3-HHB-3 (3-5-1) 5% 2-BB(F)B-3(3-7-1) 5% 3-HB—CL (4-1-1) 5% 3-HBB(F,F)—F (4-12-1) 7%

NI=75.2° C.; Tc≦−20° C.; Δn=0.095; Δ∈=4.3; Vth=2.04 V; η=9.4 mPa·s;VHR-1=99.1%; VHR-2=98.1%; VHR-3=97.8%.

The compositions in Example 1 to Example 7 have smaller viscosity thanthose of Comparative Example 1 to Comparative Example 3. Accordingly,the liquid crystal composition of the invention has excellentcharacteristics.

INDUSTRIAL APPLICABILITY

The invention provides a liquid crystal composition that satisfies atleast one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a suitable optical anisotropy, a large dielectric anisotropy,a large specific resistance, a large elastic constant, a high stabilityto ultraviolet light and a high stability to heat, or that is suitablybalanced between at least two of the characteristics. A liquid crystaldisplay device containing such a composition becomes an AM device thathas a short response time, a large voltage holding ratio, a largecontrast ratio, a long service life and so forth, and thus it can beused for a liquid crystal projector, a liquid crystal television and soforth.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

1. A liquid crystal composition having a nematic phase and comprisingthree components, wherein a first component is at least one compoundselected from the group of compounds represented by formula (1), and asecond component is at least one compound selected from the group ofcompounds represented by formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring A and ring B are each independently 1,4-cyclohexylene or1,4-phenylene, X¹ , X² and X³ are each independently hydrogen orfluorine; Y¹ is fluorine, chlorine or trifluoromethoxy.
 2. The liquidcrystal composition according to claim 1, wherein the first component isat least one compound selected from the group of compounds representedby formula (1-1) and formula (1-2):

wherein R¹ is independently alkyl having 1 to 12 carbons, alkoxy having1 to 12 carbons or alkenyl having 2 to 12 carbons.
 3. The liquid crystalcomposition according to claim 1, wherein the second component is atleast one compound selected from the group of compounds represented byformula (2-1) and formula (2-2):

wherein R² is independently alkyl having 1 to 12 carbons, alkoxy having1 to 12 carbons or alkenyl having 2 to 12 carbons.
 4. The liquid crystalcomposition according to claim 1, wherein the ratio of the firstcomponent is in the range of approximately 5% by weight to approximately50% by weight, the ratio of the second component is in the range ofapproximately 5% by weight to approximately 50% by weight, based on thetotal weight of the liquid crystal composition.
 5. The liquid crystalcomposition according to claim 1, further comprising at least onecompound selected from the group of compounds represented by formula (3)as a third component:

wherein R³ and R⁴ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring C, ring D and ring E are each independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z¹ isindependently a single bond, ethylene or carbonyloxy; and m is 0, 1 or2.
 6. The liquid crystal composition according to claim 5, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1) to formula (3-13):

wherein R³ and R⁴ are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkoxymethyl having 2 to 12 carbons,alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons inwhich arbitrary hydrogen is replaced by fluorine.
 7. The liquid crystalcomposition according to claim 5 wherein the ratio of the thirdcomponent is in the range of approximately 30% by weight toapproximately 75% by weight based on the total weight of the liquidcrystal composition.
 8. The liquid crystal composition according toclaim 1, further comprising at least one compound selected from thegroup of compounds represented by formula (4) as a fourth component:

wherein R⁵ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring F is independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, 1,3-dioxane-2,5-diylor tetrahydropyran-2,5-diyl or pyrimidine-2,5-diyl; X⁴ and X⁵ are eachindependently hydrogen or fluorine; Y² is fluorine or chlorine; and Z²is independently a single bond, ethylene, carbonyloxy ordifluoromethyleneoxy; n is 1, 2 or 3; and three of Z² are all singlebonds when n is
 3. 9. The liquid crystal composition according to claim5, further comprising at least one compound selected from the group ofcompounds represented by formula (4) as a fourth component:

wherein R⁵ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring F is independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, 1,3-dioxane-2,5-diylor tetrahydropyran-2,5-diyl or pyrimidine-2,5-diyl; X⁴ and X⁵ are eachindependently hydrogen or fluorine; Y² is fluorine or chlorine; and Z²is independently a single bond, ethylene, carbonyloxy ordifluoromethyleneoxy; n is 1, 2 or 3; and three of Z² are all singlebonds when n is
 3. 10. The liquid crystal composition according to claim8, wherein the fourth component is at least one compound selected fromthe group of compounds represented by formula (4-1) to formula (4-19):

wherein R⁵ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.
 11. The liquid crystalcomposition according to claim 9, wherein the fourth component is atleast one compound selected from the group of compounds represented byformula (4-1) to formula (4-19):

wherein R⁵ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.
 12. The liquid crystalcomposition according to claim 8, wherein the ratio of the fourthcomponent is in the range of approximately 3% by weight to approximately40% by weight based on the total weight of the liquid crystalcomposition.
 13. The liquid crystal composition according to claim 9,wherein the ratio of the fourth component is in the range ofapproximately 3% by weight to approximately 40% by weight based on thetotal weight of the liquid crystal composition.
 14. The liquid crystalcomposition according to claim 8, further including at least onecompound selected from the group of compounds represented by formula (5)as a fifth component:

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring G and ring H are eachindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, or 3,5-difluoro-1,4-phenylene; X⁶ and X⁷ areeach independently hydrogen or fluorine; Y³ is fluorine, chlorine ortrifluoromethoxy.
 15. The liquid crystal composition according to claim9, further including at least one compound selected from the group ofcompounds represented by formula (5) as a fifth component:

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons; ring G and ring H are eachindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, or 3,5-difluoro-1,4-phenylene; X⁶ and X⁷ areeach independently hydrogen or fluorine; Y³ is fluorine, chlorine ortrifluoromethoxy.
 16. The liquid crystal composition according to claim14, wherein the fifth component is at least one compound selected fromthe group of compounds represented by formula (5-1) to formula (5-5):

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.
 17. The liquid crystalcomposition according to claim 15, wherein the fifth component is atleast one compound selected from the group of compounds represented byformula (5-1) to formula (5-5):

wherein R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons or alkenyl having 2 to 12 carbons.
 18. The liquid crystalcomposition according to claim 14, wherein the ratio of the fifthcomponent is in the range of approximately 3% by weight to approximately20% by weight based on the total weight of the liquid crystalcomposition.
 19. The liquid crystal composition according to claim 15,wherein the ratio of the fifth component is in the range ofapproximately 3% by weight to approximately 20% by weight based on thetotal weight of the liquid crystal composition.
 20. The liquid crystalcomposition according to claim 1, wherein the maximum temperature of anematic phase is approximately 70° C. or higher, the optical anisotropy(25° C.) at a wavelength of 589 nanometers is approximately 0.08 ormore, and the dielectric anisotropy (25° C.) at a frequency of 1 kHz isapproximately 4 or more.
 21. A liquid crystal display device containingthe liquid crystal composition according to claim
 1. 22. The liquidcrystal display device according to claim 21, wherein an operating modeof the liquid crystal display device is a TN mode, an OCB mode, an IPSmode, a FFS mode or a PSA mode, and a driving mode of the liquid crystaldisplay device is an active matrix mode.